The present invention relates to a multilayer wiring substrate.
In depositing multiple fine wiring layers over a glass ceramic layer, insulated with a polyimide resin layer, in a conventional multilayer wiring substrate, the adhesion of the polyimide resin layer is strengthened by coating the glass ceramic layer with a silane-based adhesion promoter or the like.
The silane-based adhesion promoter coat, however, by itself cannot provide strong enough adhesion between the glass ceramic layer and the polyimide resin layer. This entails the disadvantage that, along with a growth in the size of multilayer wiring substrates, a stress due to the difference in thermal expansion coefficient between the glass ceramic layer and the polyimide resin layer increases and thereby invites peeling of the polyimide off the glass ceramics.
An object of the invention is, therefore, to provide a multilayer wiring substrate free from the above-mentioned disadvantage of the conventional substrate.